A traditional fossil fuel vehicle is usually equipped with an additional automatic start-stop subsystem for realizing taxiing start-stop control on the vehicle, and thus fuel waste and air pollution caused by engine idling are reduced. There have been following forms of start-stop systems in vehicles.
1. Separating Starter/Generator Start-Stop System
In such a system, the starter and the generator are designed separately, in which the starter is used to provide power for starting an engine, and the generator is used to provide electric energy for the starter. This system includes a high enhanced starter, an enhanced battery (usually an AGM battery), a controllable generator, an engine ECU (Electronic Control Unit) with integrated start-stop coordination program, and a sensor, etc. In this system, the engine is started by the starter separately.
2. Integrated Starter/Generator Start-Stop System
The integrated start/generator is a synchronous machine actuated by a single teeth stator and a rotor in a permanent magnet, and a driving unit may be integrated into a hybrid power transmission system. With this system, the engine may be started by revise driving from the motor.
3. i-start System
An electric control device is integrated in the generator. The engine stops when the vehicle stops at a red light, and automatically starts as soon as engaging a gear or releasing a brake pedal.
When the vehicle is driven on heavy-traffic roads, the engine will be started frequently, that is a huge test for both a spark plug and a battery. Although the start-stop systems described-above are intelligent enough, a service life of the engine will be shorten as an abrasion on the engine, and a vibration and a noise are inevitable as frequent start-stop, which severely reduces the comfort. In addition, the automatic start-stop system may work only in such conditions that a vehicle speed is 0, a rotating speed of the engine is lower than a prescribed target speed, the refrigerant is in a required range, the vacuum braking meets a required condition, an air conditioner is adjusted suitably, the braking pedal is depressed at a certain gear position (like N or P), and an electric charge level of the power battery meets a next start. Since the start-stop system is limited on many aspects, system units are required to have a high reliability and durability. Moreover, the special start-stop system increases the cost of the vehicle.